Classifications

• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
  • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
  • G03F7/004—Photosensitive materials
  • G03F7/039—Macromolecular compounds which are photodegradable, e.g. positive electron resists
  • G03F7/0392—Macromolecular compounds which are photodegradable, e.g. positive electron resists the macromolecular compound being present in a chemically amplified positive photoresist composition
  • G03F7/0397—Macromolecular compounds which are photodegradable, e.g. positive electron resists the macromolecular compound being present in a chemically amplified positive photoresist composition the macromolecular compound having an alicyclic moiety in a side chain
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S430/00—Radiation imagery chemistry: process, composition, or product thereof
  • Y10S430/1053—Imaging affecting physical property or radiation sensitive material, or producing nonplanar or printing surface - process, composition, or product: radiation sensitive composition or product or process of making binder containing
  • Y10S430/1055—Radiation sensitive composition or product or process of making
  • Y10S430/106—Binder containing
  • Y10S430/111—Polymer of unsaturated acid or ester

Definitions

• the present invention relates to a positive resist composition and a method for forming a resist pattern.
• Chemically amplified photoresist compositions that use a KrF excimer laser, ArF excimer laser, F 2 excimer laser, EUV (extreme ultraviolet light) or EB (electron beam) or the like as a light source (a radiation source) generally include a resin component (A) and an acid generator component (B) that generates an acid on irradiation dissolved in an organic solvent (C), as disclosed, for example, in Japanese Unexamined Patent Application, First Publication No. 2003-167347 (patent reference 1).
• photoresist compositions require favorable lithography characteristics (including resolution, depth of focus characteristics, and resist pattern shape and the like).
• the photoresist compositions also require improvements beyond the conventionally observed level of defects (surface defects) within the developed resist pattern.
• defects refer to general abnormalities detected by inspection of the resist pattern following developing, from directly above the resist pattern, using a surface defect inspection device (brand name: KLA) from KLA Tencor Corporation.
• KLA surface defect inspection device
• these abnormalities include post-developing scum, foam, dust, bridges across different portions of the resist pattern, color irregularities, and precipitated deposits and the like.
• the present invention takes the above circumstances into consideration, with an object of providing a positive resist composition that is capable of reducing the level of defects, as well as a method for forming a resist pattern that uses the composition.
• a first aspect of the present invention is a positive resist composition including a resin component (A) that exhibits increased alkali solubility under the action of acid, and an acid generator component (B) that generates acid on exposure, wherein
• the component (A) is a copolymer (A1) that includes a structural unit (a1) derived from an acrylate that contains an acid dissociable, dissolution inhibiting group, a structural unit (a2) derived from an ⁇ -lower alkyl acrylate that contains a lactone ring, and a structural unit (a3) derived from an ( ⁇ -lower alkyl)acrylate that contains a polar group-containing polycyclic group, and
• the measured value of the contact angle at the surface of the resist film, following application of a developing solution to the surface of the resist film is no higher than 40 degrees.
• a second aspect is a positive resist composition including a resin component (A) that exhibits increased alkali solubility under the action of acid, and an acid generator component (B) that generates acid on exposure, wherein when a resist film is formed from the resist composition on top of a support, the measured value of the contact angle at the surface of the resist film, following application of a developing solution to the surface of the resist film, is no higher than 40 degrees.
• a third aspect is a positive resist composition including a resin component (A) that exhibits increased alkali solubility under the action of acid, and an acid generator component (B) that generates acid on exposure, wherein the composition satisfies the conditions (1) and (2) listed below.
• the component (A) is a copolymer (A1′) that includes a structural unit (a1′) derived from an ( ⁇ -lower alkyl)acrylate that contains an acid dissociable, dissolution inhibiting group, a structural unit (a2′) derived from an ( ⁇ -lower alkyl)acrylate that contains a lactone ring, and a structural unit (a3′) derived from an ( ⁇ -lower alkyl)acrylate that contains a polar group-containing polycyclic group.
• a fourth aspect of the present invention is a method for forming a resist pattern that includes the steps of applying a positive resist composition according to any of the above first through third aspects to a substrate, conducting a prebake, performing selective exposure, conducting PEB (post exposure baking), and performing alkali developing to form the resist pattern.
• ( ⁇ -lower alkyl)acrylate is a generic term that includes ⁇ -lower alkyl acrylates such as methacrylate, and/or acrylate.
• ⁇ -lower alkyl acrylate refers to a structure in which the hydrogen atom bonded to the ⁇ -carbon atom of an acrylate has been substituted with a lower alkyl group.
• structural unit refers to a monomer unit that contributes to the formation of a polymer.
• structural unit derived from an acrylate refers to a structural unit that is formed by cleavage of the ethylenic double bond of an acrylate ester.
• structural unit derived from an ⁇ -lower alkyl acrylate refers to a structural unit that is formed by cleavage of the ethylenic double bond of an ⁇ -lower alkyl acrylate ester.
• structural unit derived from an ( ⁇ -lower alkyl)acrylate refers to a structural unit that is formed by cleavage of the ethylenic double bond of an ( ⁇ -lower alkyl)acrylate ester.
• exposure is used as a general concept that includes irradiation with any form of radiation.
• the present invention is able to provide a positive resist composition that is capable of reducing the level of defects, as well as a method for forming a resist pattern that uses the composition.
• a positive resist composition of the first aspect includes a resin component (A) that exhibits increased alkali solubility under the action of acid, and an acid generator component (B) that generates acid on exposure, wherein
• the component (A) is a copolymer (A1) that includes a structural unit (a1) derived from an acrylate that contains an acid dissociable, dissolution inhibiting group, a structural unit (a2) derived from an ⁇ -lower alkyl acrylate that contains a lactone ring, and a structural unit (a3) derived from an ( ⁇ -lower alkyl)acrylate that contains a polar group-containing polycyclic group, and when a resist film is formed from the resist composition on top of a support, the measured value of the contact angle at the surface of the resist film, following application of a developing solution to the surface of the resist film, is no higher than 40 degrees.
• the level of defects can be reduced. Furthermore, the required lithography characteristics can also be obtained.
• Copolymer (A1) [Hereafter also Referred to as Component (A1)]
• a hydrogen atom is bonded to the ⁇ -carbon atom.
• the acid dissociable, dissolution inhibiting group of the structural unit (a1) is a group that exhibits an alkali dissolution inhibiting effect that renders the entire component (A1) alkali-insoluble prior to exposure, but then dissociates under the action of acid generated from the acid generator (B) following exposure, causing the entire component (A1) to change to an alkali-soluble state.
• the acid dissociable, dissolution inhibiting group can be selected appropriately from the multitude of such groups proposed for use within resins for resist compositions used with an ArF excimer laser.
• groups that form either a cyclic or chain-like tertiary alkyl ester with the carboxyl group of acrylic acid, or groups that form a cyclic or chain-like alkoxyalkyl group are the most widely known.
• a cyclic or chain-like alkoxyalkyl ester refers to a structure in which the hydrogen atom of a carboxyl group has been substituted with an alkoxyalkyl group to form an ester, so that the alkoxyalkyl group is bonded to the terminal oxygen atom of the carbonyloxy group (—C(O)—O—), and when an acid acts on this alkoxyalkyl ester, the bond between the oxygen atom and the alkoxyalkyl group is broken.
• Examples of these types of cyclic or chain-like alkoxyalkyl groups include a 1-methoxymethyl group, 1-ethoxyethyl group, 1-isopropoxyethyl group, 1-cyclohexyloxyethyl group, 2-adamantoxymethyl group, 1-methyladamantoxymethyl group, and 4-oxo-2-adamantoxymethyl group.
• Examples of acid dissociable, dissolution inhibiting groups that form a chain-like tertiary alkyl ester include a tert-butyl group or tert-amyl group.
• the structural unit (a1) structural units that include an acid dissociable, dissolution inhibiting group that contains a cyclic group, and particularly an alicyclic group, are preferred.
• the alicyclic group may be either a monocyclic or a polycyclic group, and can be selected appropriately from the multitude of such groups proposed for use within ArF resists, although from the viewpoint of etching resistance, a polycyclic alicyclic group is preferred.
• the alicyclic group is preferably a hydrocarbon group, and is preferably saturated.
• Examples of suitable monocyclic alicyclic groups include groups in which one hydrogen atom has been removed from a cycloalkane.
• Examples of suitable polycyclic alicyclic groups include groups in which one hydrogen atom has been removed from a bicycloalkane, tricycloalkane or tetracycloalkane or the like.
• Suitable monocyclic groups include a cyclopentyl group or cyclohexyl group.
• suitable polycyclic groups include groups in which one hydrogen atom has been removed from a polycycloalkane such as adamantane, norbornane, isobornane, tricyclodecane or tetracyclododecane.
• an adamantyl group in which one hydrogen atom has been removed from adamantane a norbornyl group in which one hydrogen atom has been removed from norbornane, a tricyclodecanyl group in which one hydrogen atom has been removed from tricyclodecane, and a tetracyclododecanyl group in which one hydrogen atom has been removed from tetracyclododecane are preferred industrially.
• the structural unit (a1) is preferably at least one unit selected from the general formulas (I), (II) and (III) shown below.
• R 1 represents a lower alkyl group.
• R 2 and R 3 each represent, independently, a lower alkyl group.
• R 4 represents a tertiary alkyl group.
• the group R 1 is preferably a straight-chain or branched lower alkyl group of 1 to 5 carbon atoms, and specific examples include a methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, isobutyl group, pentyl group, isopentyl group, and neopentyl group. Of these, a methyl group or ethyl group is preferred from the viewpoint of industrial availability.
• the groups R 2 and R 3 each preferably represent, independently, a straight-chain or branched lower alkyl group of 1 to 5 carbon atoms. Of these groups, the case in which R 2 and R 3 are both methyl groups is preferred industrially, and a structural unit derived from 2-(1-adamantyl)-2-propyl acrylate is a specific example.
• the group R 4 is preferably a chain-like tertiary alkyl group or a cyclic tertiary alkyl group.
• chain-like tertiary alkyl groups include a tert-butyl group or tert-amyl group, although the case in which R 4 is a tert-butyl group is preferred industrially.
• a tertiary alkyl group refers to an alkyl group that includes a tertiary carbon atom.
• cyclic tertiary alkyl groups include the same groups as those exemplified above in relation to the “acid dissociable, dissolution inhibiting group that contains an alicyclic group”, and specific examples include a 2-methyl-2-adamantyl group, 2-ethyl-2-adamantyl group, 2-(1-adamantyl)-2-propyl group, 1-ethylcyclohexyl group, 1-ethylcyclopentyl group, 1-methylcyclohexyl group or 1-methylcyclopentyl group.
• the group —COOR 4 may be bonded to either position 3 or 4 of the tetracyclododecanyl group shown in the formula, although the bonding position cannot be further specified.
• the carboxyl group residue of the acrylate structural unit may be bonded to either position 8 or 9 of the tetracyclododecanyl group, although similarly, the bonding position cannot be further specified.
• the structural unit (a1) may use either a single structural unit, or a combination of two or more different structural units.
• the proportion of the structural unit (a1), relative to the combined total of all the structural units that constitute the component (A1), is typically within a range from 20 to 60 mol %, and is preferably from 30 to 50 mol %, and most preferably from 35 to 45 mol %.
• a lower alkyl group is bonded to the ⁇ -carbon atom.
• Examples of the structural unit (a2) include structural units in which a monocyclic group formed from a lactone ring or a polycyclic group that includes a lactone ring is bonded to the ester side-chain portion of an ⁇ -lower alkyl acrylate.
• lactone ring refers to a single ring containing a —O—C(O)— structure, and this ring is counted as the first ring. Accordingly, in this description, the case in which the only ring structure is the lactone ring is referred to as a monocyclic group, and groups containing other ring structures are described as polycyclic groups regardless of the structure of the other rings.
• the structural unit (a2) include monocyclic groups in which one hydrogen atom has been removed from ⁇ -butyrolactone, and polycyclic groups in which one hydrogen atom has been removed from a lactone ring-containing bicycloalkane.
• the lower alkyl group bonded to the ⁇ -carbon atom is preferably a straight-chain or branched alkyl group of 1 to 5 carbon atoms, and examples of suitable groups include a methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, pentyl group, isopentyl group, and neopentyl group.
• a methyl group is preferred industrially.
• the structural unit (a2) is preferably at least one unit selected from the general formulas (IV) through (VII) shown below.
• R′ represents a lower alkyl group
• R 5 and R 6 each represent, independently, a hydrogen atom or a lower alkyl group.
• R′ represents a lower alkyl group, and m represents either 0 or 1.
• R′ represents a lower alkyl group.
• R′ represents a lower alkyl group.
• R′ The details relating to the lower alkyl group represented by R′ are identical to those described above for the lower alkyl group bonded to the ⁇ -carbon atom.
• R 5 and R 6 each represent, independently, a hydrogen atom or a lower alkyl group, and preferably a hydrogen atom.
• Suitable lower alkyl groups for the groups R 5 and R 6 are preferably straight-chain or branched alkyl groups of 1 to 5 carbon atoms, and specific examples include a methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, pentyl group, isopentyl group, and neopentyl group.
• a methyl group is preferred industrially.
• structural units represented by the general formulas (IV) through (VII) are preferred in terms of reducing defects, and of the possible structural units represented by the formula (IV), ⁇ -methacryloyloxy- ⁇ -butyrolactone, in which R′ is a methyl group, R 5 and R 6 are both hydrogen atoms, and the position of the ester linkage between the methacrylate ester and the ⁇ -butyrolactone is at the ⁇ -position of the lactone ring, is the most desirable.
• the structural unit (a2) may use either a single structural unit, or a combination of two or more different structural units.
• the proportion of the structural unit (a2), relative to the combined total of all the structural units that constitute the component (A1), is typically within a range from 20 to 60 mol %, and is preferably from 20 to 50 mol %, and most preferably from 30 to 45 mol %. Ensuring that this proportion is at least as large as the lower limit of the above range improves the lithography characteristics, whereas ensuring that the proportion is no greater than the upper limit of the above range enables a favorable balance to be achieved with the other structural units.
• Including the structural unit (a3) increases the hydrophilicity of the entire component (A1), thereby improving the affinity with the developing solution, improving the alkali solubility within the exposed portions of the resist, and contributing to an improvement in the resolution.
• either a lower alkyl group or a hydrogen atom may be bonded to the ⁇ -carbon atom, although a hydrogen atom is preferred. Details of suitable lower alkyl groups are the same as those described above for R′.
• Examples of the polar group include a hydroxyl group, cyano group, carboxyl group, or amino group or the like, although a hydroxyl group is particularly preferred.
• polycyclic group examples include polycyclic alicyclic hydrocarbon groups (also abbreviated as “polycyclic groups”).
• the polycyclic group can be selected appropriately from the same multitude of polycyclic groups exemplified above in relation to the structural unit (a1).
• the structural unit (a3) is preferably at least one unit selected from the general formulas (VIII) through (IX) shown below.
• R represents a hydrogen atom or a lower alkyl group, and n represents an integer from 1 to 3.
• R represents a hydrogen atom or a lower alkyl group, and k represents an integer from 1 to 3.
• R groups are the same as those described above for the lower alkyl group or hydrogen atom bonded to the ⁇ -carbon atom.
• cyano group is preferably bonded to position 5 or position 6 of the norbornyl group.
• the structural unit (a3) may use either a single structural unit, or a combination of two or more different structural units.
• the proportion of the structural unit (a3), relative to the combined total of all the structural units that constitute the component (A1), is typically within a range from 10 to 50 mol %, and is preferably from 15 to 40 mol %, and most preferably from 20 to 30 mol %.
• the component (A1) may include structural units other than the aforementioned structural units (a1) through (a3), but the combined total of these structural units (a1) through (a3), relative to the combined total of all the structural units, is typically at least 70 mol %, and is preferably 80 mol % or greater, and most preferably 100 mol %.
• a structural unit (a4) besides the structural units (a1) through (a3) may be any other structural unit that cannot be classified as one of the above structural units (a1) through (a3), and there are no particular restrictions.
• structural units that contain a polycyclic alicyclic hydrocarbon group, and are derived from an ( ⁇ -lower alkyl)acrylate are preferred.
• the polycyclic alicyclic hydrocarbon group include, for example, the same multitude of groups listed above in relation to the structural unit (a1), and of these, in terms of industrial availability and the like, one or more groups selected from amongst a tricyclodecanyl group, adamantyl group, tetracyclododecanyl group, norbornyl group, and isobornyl group is preferred.
• structural unit (a4) include units of the structures (X) to (XII) shown below.
• R represents a hydrogen atom or a lower alkyl group
• This structural unit typically exists as a mixture of the isomers in which the bonding position is either position 5 or position 6.
• R represents a hydrogen atom or a lower alkyl group
• R represents a hydrogen atom or a lower alkyl group
• the proportion of the structural unit (a4), relative to the combined total of all the structural units that constitute the component (A1), is typically within a range from 1 to 25 mol %, and is preferably from 5 to 20 mol %.
• the component (A1) is preferably a copolymer that includes at least the structural units represented by the chemical formulas shown below, and is even more preferably a copolymer formed solely from these structural units.
• the component (A1) may include either a single resin, or a mixture of two or more different resins.
• the component (A1) can be obtained, for example, by a conventional radical polymerization or the like of the monomers corresponding with each of the structural units, using a radical polymerization initiator such as azobisisobutyronitrile (AIBN).
• a radical polymerization initiator such as azobisisobutyronitrile (AIBN).
• the value is typically no more than approximately 30,000, and is preferably no more than 20,000, even more preferably 12,000 or lower, and is most preferably 10,000 or lower.
• the weight average molecular weight is preferably at least 4,000, and even more preferably 5,000 or greater.
• the component (B) can use any of the known acid generators used in conventional chemically amplified resist compositions without any particular restrictions.
• Examples of the types of acid generators that have been used are numerous, and include onium salt-based acid generators such as iodonium salts and sulfonium salts, oxime sulfonate-based acid generators, diazomethane-based acid generators such as bisalkyl or bisaryl sulfonyl diazomethanes, and poly(bis-sulfonyl)diazomethanes, iminosulfonate-based acid generators, and disulfone-based acid generators.
• onium salt-based acid generators such as iodonium salts and sulfonium salts
• oxime sulfonate-based acid generators such as bisalkyl or bisaryl sulfonyl diazomethanes
• poly(bis-sulfonyl)diazomethanes iminosulfonate-based acid generators, and disulfone-based acid generators.
• suitable onium salt-based acid generators include diphenyliodonium trifluoromethanesulfonate or nonafluorobutanesulfonate, bis(4-tert-butylphenyl)iodonium trifluoromethanesulfonate or nonafluorobutanesulfonate, triphenylsulfonium trifluoromethanesulfonate, heptafluoropropanesulfonate or nonafluorobutanesulfonate, tri(4-methylphenyl)sulfonium trifluoromethanesulfonate, heptafluoropropanesulfonate or nonafluorobutanesulfonate, dimethyl(4-hydroxynaphthyl)sulfonium trifluoromethanesulfonate, heptafluoropropanesulfonate or nonafluorobutanesulfonate, monophenyl
• Suitable oxime sulfonate-based acid generators include ⁇ -(methylsulfonyloxyimino)-phenyl acetonitrile, ⁇ -(methylsulfonyloxyimino)-p-methoxyphenyl acetonitrile, ⁇ -(trifluoromethylsulfonyloxyimino)-phenyl acetonitrile, ⁇ -(trifluoromethylsulfonyloxyimino)-p-methoxyphenyl acetonitrile, ⁇ -(ethylsulfonyloxyimino)-p-methoxyphenyl acetonitrile, ⁇ -(propylsulfonyloxyimino)-p-methylphenyl acetonitrile, and ⁇ -(methylsulfonyloxyimino)-p-bromophenyl acetonitrile. Of these, ⁇ -(methylsulf
• suitable bisalkyl or bisaryl sulfonyl diazomethanes include bis(isopropylsulfonyl)diazomethane, bis(p-toluenesulfonyl)diazomethane, bis(1,1-dimethylethylsulfonyl)diazomethane, bis(cyclohexylsulfonyl)diazomethane, and bis(2,4-dimethylphenylsulfonyl)diazomethane.
• poly(bis-sulfonyl)diazomethanes include the structures shown below, such as 1,3-bis(phenylsulfonyldiazomethylsulfonyl)propane (compound A), 1,4-bis(phenylsulfonyldiazomethylsulfonyl)butane (compound B), 1,6-bis(phenylsulfonyldiazomethylsulfonyl)hexane (compound C), 1,10-bis(phenylsulfonyldiazomethylsulfonyl)decane (compound D), 1,2-bis(cyclohexylsulfonyldiazomethylsulfonyl)ethane (compound E), 1,3-bis(cyclohexylsulfonyldiazomethylsulfonyl)propane (compound F), 1,6-bis(cyclohexylsulfonyldiazo
• the component (B) preferably uses an onium salt with a fluorinated alkylsulfonate ion as the anion.
• component (B) the use of at least one sulfonium compound selected from the group consisting of structural units represented by general formulas (b-1) and (b-2) shown below is also preferred.
• X represents an alkylene group of 2 to 6 carbon atoms in which at least one hydrogen atom has been substituted with a fluorine atom
• Y and Z each represent, independently, an alkyl group of 1 to 10 carbon atoms in which at least one hydrogen atom has been substituted with a fluorine atom
• R 11 to R 13 each represent, independently, an aryl group or an alkyl group, although at least one of the groups R 11 to R 13 is an aryl group.
• the group X is a straight-chain or branched alkylene group in which at least one hydrogen atom has been substituted with a fluorine atom, and the number of carbon atoms within the alkylene group is typically within a range from 2 to 6, and preferably from 3 to 5, and is most preferably 3.
• Y and Z each represent, independently, a straight-chain or branched alkyl group in which at least one hydrogen atom has been substituted with a fluorine atom, and the number of carbon atoms within the alkyl group is typically within a range from 1 to 10, and preferably from 1 to 7, and most preferably from 1 to 3.
• the fluorine atom proportion within the alkylene group or alkyl groups, namely the fluorination ratio, is preferably within a range from 70 to 100%, and even more preferably from 90 to 100%, and perfluoroalkylene or perfluoroalkyl groups in which all of the hydrogen atoms have been substituted with fluorine atoms are the most desirable.
• R 11 to R 13 each represent, independently, an aryl group or an alkyl group.
• At least one group represents an aryl group.
• Compounds in which at least two of R 11 to R 13 represent aryl groups are preferred, and compounds in which all of R 11 to R 13 are aryl groups are the most preferred.
• aryl groups of R 11 to R 13 there are no particular restrictions on the aryl groups of R 11 to R 13 , and suitable examples include aryl groups of 6 to 20 carbon atoms, such as phenyl groups and naphthyl groups, which may, or may not, be substituted with alkyl groups, alkoxy groups, and/or halogen atoms and the like. In terms of enabling low cost synthesis, aryl groups of 6 to 10 carbon atoms are preferred.
• alkyl groups of R 11 to R 13 there are no particular restrictions on the alkyl groups of R 11 to R 13 , and suitable examples include straight-chain, branched, or cyclic alkyl groups of 1 to 10 carbon atoms. From the viewpoint of achieving excellent resolution, alkyl groups of 1 to 5 carbon atoms are preferred. Specific examples include a methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, n-pentyl group, cyclopentyl group, hexyl group, cyclohexyl group, nonyl group, and decanyl group, although in terms of achieving superior resolution and enabling low cost synthesis, a methyl group is the most desirable.
• sulfonium compounds can be used either alone, or in combinations of two or more different compounds.
• the component (B) may use either a single acid generator, or a combination of two or more different acid generators.
• the quantity used of the component (B) is typically within a range from 0.5 to 30 parts by weight, and preferably from 1 to 10 parts by weight, per 100 parts by weight of the component (A). At quantities less than the above range, there is a danger that pattern formation may not proceed satisfactorily, whereas if the quantity exceeds the above range, achieving a uniform solution becomes difficult, and there is a danger of a deterioration in the storage stability.
• a nitrogen-containing organic compound (D) (hereafter referred to as the component (D)) can be added as an optional component.
• a lower aliphatic amine refers to an alkyl or alkyl alcohol amine of no more than 5 carbon atoms
• these secondary and tertiary amines include trimethylamine, diethylamine, triethylamine, di-n-propylamine, tri-n-propylamine, tripentylamine, diethanolamine, triethanolamine and triisopropanolamine, and of these, tertiary alkanolamines such as triethanolamine and triisopropanolamine are particularly preferred.
• the component (D) is typically used in a quantity within a range from 0.01 to 5.0 parts by weight per 100 parts by weight of the component (A).
• an organic carboxylic acid, or a phosphorus oxo acid or derivative thereof can also be added as another optional component (E) (hereafter referred to as the component (E)).
• the component (D) and the component (E) can be used in combination, or either one can also be used alone.
• suitable organic carboxylic acids include malonic acid, citric acid, malic acid, succinic acid, benzoic acid, and salicylic acid.
• Suitable phosphorus oxo acids or derivatives thereof include phosphoric acid or derivatives thereof such as esters, including phosphoric acid, di-n-butyl phosphate, and diphenyl phosphate; phosphonic acid or derivatives thereof such as esters, including phosphonic acid, dimethyl phosphonate, di-n-butyl phosphonate, phenylphosphonic acid, diphenyl phosphonate, and dibenzyl phosphonate; and phosphinic acid or derivatives thereof such as esters, including phosphinic acid and phenylphosphinic acid, and of these, phosphonic acid is particularly preferred.
• phosphoric acid or derivatives thereof such as esters, including phosphoric acid, di-n-butyl phosphate, and diphenyl phosphate
• phosphonic acid or derivatives thereof such as esters, including phosphonic acid, dimethyl phosphonate, di-n-butyl phosphonate, phenylphosphonic acid, di
• the component (E) is typically used in a quantity within a range from 0.01 to 5.0 parts by weight per 100 parts by weight of the component (A).
• a positive resist composition of the present invention can be produced by dissolving the materials in an organic solvent.
• the organic solvent may be any solvent capable of dissolving the various components to generate a uniform solution, and one or more solvents selected from known materials used as the solvents for conventional chemically amplified resists can be used.
• the solvent include ketones such as ⁇ -butyrolactone, acetone, methyl ethyl ketone, cyclohexanone, methyl isoamyl ketone and 2-heptanone; polyhydric alcohols and derivatives thereof such as ethylene glycol, ethylene glycol monoacetate, diethylene glycol, diethylene glycol monoacetate, propylene glycol, propylene glycol monoacetate, dipropylene glycol, or the monomethyl ether, monoethyl ether, monopropyl ether, monobutyl ether or monophenyl ether of dipropylene glycol monoacetate; cyclic ethers such as dioxane; and esters such as methyl lactate, ethyl lactate (EL), methyl acetate, ethyl acetate, butyl acetate, methyl pyruvate, ethyl pyruvate, methyl methoxypropionate, and ethyl
• organic solvents can be used either alone, or as a mixed solvent of two or more different solvents.
• mixed solvents of propylene glycol monomethyl ether acetate (PGMEA) and a polar solvent are preferred.
• the blend ratio (weight ratio) in such mixed solvents can be set in accordance with factors such as the co-solubility of the PGMEA and the polar solvent, the ratio is preferably within a range from 1:9 to 9:1, and even more preferably from 2:8 to 8:2.
• the weight ratio PGMEA:EL is preferably within a range from 2:8 to 8:2, and even more preferably from 3:7 to 7:3.
• organic solvent mixed solvents containing at least one of PGMEA and EL, together with ⁇ -butyrolactone, are also preferred.
• the weight ratio of the former and latter components in the mixed solvent is preferably within a range from 70:30 to 95:5.
• the quantity used of the organic solvent should provide a concentration that enables favorable application of the solution to a substrate or the like, should be set in accordance with the required coating film thickness, and is typically set so that the solid fraction concentration within the resist composition falls within a range from 2 to 20% by weight, and even more preferably from 5 to 15% by weight.
• miscible additives can also be added to a positive resist composition of the present invention according to need, and examples include additive resins for improving the properties of the resist film, surfactants for improving the ease of application, dissolution inhibitors, plasticizers, stabilizers, colorants, halation prevention agents, and dyes.
• the measured value of the contact angle at the surface of the resist film, following application of a developing solution to the surface of the resist film is preferably no higher than 40 degrees.
• the first aspect, the second aspect, and the third aspect preferably all satisfy the requirement for a specific contact angle.
• the contact angle is also preferably at least 25 degrees, and even more preferably 30 degrees or greater. By ensuring that the contact angle satisfies this range, the level of defects can be reduced even further. Furthermore, the lithography characteristics also improve.
• a preferred contact angle value is within a range from 30 to 40 degrees, even more preferably from 32 to 40 degrees, even more preferably from 35 to 40 degrees, and most preferably from 36 to 39 degrees.
• the contact angle can be altered by adjusting the nature and blend quantities of the structural units within the component (A1), or by adjusting the nature and blend quantities of other components such as the component (B) as is described in further detail below.
• the method of measuring the contact angle is described in detail in the description relating to the second aspect.
• the level of defects can be reduced. Furthermore, the required lithography characteristics can also be obtained. Moreover, the sensitivity also improves.
• the required lithography characteristics can also be obtained using a shrink process described below.
• narrowing can be conducted with the temperature during the shrink step set to a lower temperature than is conventionally employed, which is particularly favorable in terms of the apparatus and the handling.
• a resist pattern is obtained by applying the positive resist composition to a substrate, conducting a prebake (PAB (post applied bake)), performing selective exposure, and then conducting PEB (post exposure baking) and performing alkali developing, but in the alkali developing step, following dissolution and removal of the exposed portions of the resist using the alkali developing solution, any residual developing solution and the like is usually removed by rinsing with pure water.
• PAB post applied bake
• PEB post exposure baking
• the positive resist composition of this first aspect generates a resist film that exhibits a small contact angle at the resist surface, meaning the surface is readily wet (has a high level of hydrophilicity)
• the affinity with comparatively hydrophobic solid components that can cause defects is reduced, meaning these deposits and residual substances can be readily removed from the resist film surface during the alkali developing and rinsing steps, thereby leading to a reduction in the level of defects.
• the second aspect is a positive resist composition including a resin component (A) that exhibits increased alkali solubility under the action of acid, and an acid generator component (B) that generates acid on exposure, wherein when a resist film is formed from the resist composition on top of a support, the measured value of the contact angle at the surface of the resist film, following application of a developing solution to the surface of the resist film, is no higher than 40 degrees.
• the level of defects can be reduced.
• the lower limit for the contact angle is typically at least 25 degrees, and preferably 30 degrees or greater.
• the measured value of the contact angle is preferably within a range from 30 to 40 degrees, even more preferably from 32 to 40 degrees, even more preferably from 35 to 40 degrees, and most preferably from 36 to 39 degrees.
• the most preferred range for the measured value of the contact angle is from 36 to 39 degrees.
• the contact angle is measured in the manner described below.
• the component (A) preferably contains a structural unit (a1′) derived from an ( ⁇ -lower alkyl)acrylate that contains an acid dissociable, dissolution inhibiting group, and a structural unit (a2′) derived from an ( ⁇ -lower alkyl)acrylate that contains a lactone ring.
• This structural unit is the same as that described below for the third aspect.
• a preferred proportion for the structural unit (a1′) within the component (A) is the same as the proportion of the structural unit (a1′) within the copolymer (A1′) according to the third aspect described below.
• This structural unit is the same as that described below for the third aspect.
• a preferred proportion for the structural unit (a2′) within the component (A) is the same as the proportion of the structural unit (a2′) within the copolymer (A1′) according to the third aspect described below.
• the component (A) is preferably a copolymer (A1′) that includes the structural unit (a1′), the structural unit (a2′), and a structural unit (a3′) derived from an ( ⁇ -lower alkyl)acrylate that contains a polar group-containing polycyclic group.
• the contact angle can be adjusted to a value within the preferred range using, for example, the methods described below.
• a copolymer in which, as per the first aspect, the structural unit (a1) is used as the structural unit (a1′) and the structural unit (a2) is used as the structural unit (a2′), then the value of the contact angle can easily be adjusted to a value of 40 degrees or lower. Moreover, the use of a copolymer (A) that includes a structural unit (a3) as well as the structural unit (a1) and the structural unit (a2) is particularly preferred.
• the value of the contact angle of the resist composition can also be adjusted to a value of 40 degrees or lower by mixing together a plurality of copolymers that each contain the same structural units.
• the expression “the same structural units” refers to structural units of the same chemical structure.
• a resist composition with a contact angle no higher than 40 degrees can be obtained.
• a first copolymer and a second copolymer are used.
• copolymers are formed using the same structural units, and the proportion of each of the structural units is the same within each copolymer, but the production lots for the copolymers are different.
• the target resist composition is produced as a first resist composition in which the component (A) of the base resin is formed from 100% by weight of the first copolymer.
• the contact angle for this first resist composition is then measured in the manner described above. This measured value is deemed X1.
• a second resist composition is produced in which the component (A) of the base resin is formed from 100% by weight of the second copolymer.
• the contact angle for this second resist composition is also measured in the manner described above. This measured value is deemed X2.
• the respective mixing proportions of the first copolymer and the second copolymer within a resist composition formed using a component (A) that contains a mixture of both copolymers are then calculated so that the measured value for the contact angle of the mixed resist composition is no higher than 40 degrees.
• a resist composition is produced using a component (A) in which the first copolymer and the second copolymer are mixed together using these proportions, then a resist composition can be obtained for which the measured value of the contact angle is no higher than 40 degrees.
• the plurality of copolymers that are mixed together preferably contain the same structural units.
• copolymers that are mixed may be any number of 2 or greater, although the number is preferably from 2 to 3, and is most preferably 2.
• the contact angle values for the plurality of copolymers that undergo mixing preferably include at least one copolymer for which the measured value of the contact angle is at least 40 degrees, and one copolymer for which the measured value of the contact angle is less than 40 degrees.
• the contact angle for the former copolymer is even more preferably greater than 40 degrees, and is most preferably within a range from 42 to 50 degrees.
• the contact angle for the latter copolymer is most preferably within a range from 30 to 34 degrees.
• the make-up of the compositions besides the nature of the component (A) is preferably set in the manner described below in example 1, and the contact angle is then measured for the thus prepared resist compositions.
• the contact angles are measured, and the respective mixing proportions for the copolymers within the component (A) are determined, then if, for example, factors other than the nature of the component (A) are altered slightly in order to formulate a composition that is ideal for an ArF excimer laser, the effects of the present invention can still be realized. As a result, the mixing proportions of the copolymers within the component (A) can be determined relatively easily.
• the contact angle can be altered by adjusting the nature and blend quantities of the structural units of the copolymer (A1′), or by adjusting the nature and blend quantities of the other components such as the component (B).
• Suitable methods include: increasing the blend quantities of structural units with hydrophilic regions, such as the structural unit (a2′) and the structural unit (a3′); selecting an acid generator that contains a hydrophilic group as the component (B); and adding a compound that contains a hydrophilic group as an additive.
• the second aspect enables a reduction in the level of defects to be achieved.
• a resist pattern is obtained by applying the positive resist composition to a substrate, conducting a prebake, performing selective exposure, and then conducting PEB (post exposure baking) and performing alkali developing, but in the alkali developing step, following dissolution and removal of the exposed portions of the resist using the alkali developing solution, any residual developing solution and the like is usually removed by rinsing with pure water.
• PEB post exposure baking
• the positive resist composition of this second aspect generates a resist film that exhibits a small contact angle at the resist surface, meaning the surface is readily wet (has a high level of hydrophilicity)
• the affinity with comparatively hydrophobic solid components that can cause defects is reduced, meaning these deposits and residual substances can be readily removed from the resist film surface during the alkali developing and rinsing steps, thereby leading to a reduction in the level of defects.
• a positive resist composition of the third aspect includes a resin component (A) that exhibits increased alkali solubility under the action of acid, and an acid generator component (B) that generates acid on exposure, wherein the composition satisfies the conditions (1) and (2) listed below.
• the component (A) is a copolymer (A1′) that includes a structural unit (a1′) derived from an ( ⁇ -lower alkyl)acrylate that contains an acid dissociable, dissolution inhibiting group, a structural unit (a2′) derived from an ( ⁇ -lower alkyl)acrylate that contains a lactone ring, and a structural unit (a3′) derived from an ( ⁇ -lower alkyl)acrylate that contains a polar group-containing polycyclic group.
• Copolymer (A1′) [hereafter also referred to as Component (A1′)]
• the structural unit (a1′) corresponds with the structural unit (a1) described in relation to the aforementioned component (A1).
• the structural unit (a1′) differs from the structural unit (a1) in that the body bonded to the ⁇ -carbon atom is not restricted to a hydrogen atom, but may be either a hydrogen atom or a lower alkyl group.
• a hydrogen atom is preferably bonded to the ⁇ -carbon atom.
• the structural unit (a1′) is preferably at least one unit selected from the general formulas (I′) through (III′) shown below.
• R represents a hydrogen atom or a lower alkyl group
• R 1 represents a lower alkyl group
• R and R 1 are as defined above.
• R represents a hydrogen atom or a lower alkyl group
• R 2 and R 3 each represent, independently, a lower alkyl group.
• R, R 2 and R 3 are as defined above.
• R represents a hydrogen atom or a lower alkyl group
• R 4 represents a tertiary alkyl group
• R and R 4 are as defined above.
• the structural unit (a2′) corresponds with the structural unit (a2) described in relation to the aforementioned component (A1).
• the structural unit (a2′) differs from the structural unit (a2) in that the group bonded to the ⁇ -carbon atom is not restricted to a lower alkyl group, but may be either a hydrogen atom or a lower alkyl group.
• a lower alkyl group is preferably bonded to the ⁇ -carbon atom.
• structural unit (a2′) is preferably at least one unit selected from the general formulas (IV′) through (VII′) shown below.
• R represents a hydrogen atom or a lower alkyl group
• R 5 and R 6 each represent, independently, a hydrogen atom or a lower alkyl group.
• R, R 5 and R 6 are as defined above.
• R represents a hydrogen atom or a lower alkyl group, and m is either 0 or 1.
• R and m are as defined above.
• R represents a hydrogen atom or a lower alkyl group.
• R is as defined above.
• R represents a hydrogen atom or a lower alkyl group.
• R is as defined above.
• the structural unit (a3′) is the same as the structural unit (a3).
• the structural unit (a3′) is preferably at least one unit selected from the general formulas (VIII′) through (IX′) shown below.
• R represents a hydrogen atom or a lower alkyl group, and n represents an integer from 1 to 3.
• R represents a hydrogen atom or a lower alkyl group, and k represents an integer from 1 to 3.
• the component (A1′) may include structural units other than the aforementioned structural units (a1′) through (a3′), but the combined total of these structural units (a1′) through (a3′), relative to the combined total of all the structural units, is typically at least 70 mol %, and is preferably 80 mol % or greater, and most preferably 100 mol %.
• a structural unit (a4′) besides the structural units (a1′) through (a3′) may be any other structural unit that cannot be classified as one of the above structural units (a1′) through (a3′), and there are no particular restrictions.
• the structural unit (a4′) corresponds with the structural unit (a4) described in relation to the aforementioned component (A1), and can employ the same types of structural units.
• the component (A1′) is preferably a copolymer that includes at least the structural units represented by the chemical formulas shown below, and is even more preferably a copolymer formed solely from these structural units.
• compositions that also satisfies the conditions of the first aspect is particularly desirable.
• the component (A1′) may include either a single resin, or a mixture of two or more different resins.
• the component (A1′) can be obtained, for example, by a conventional radical polymerization or the like of the monomers corresponding with each of the structural units, using a radical polymerization initiator such as azobisisobutyronitrile (AIBN).
• a radical polymerization initiator such as azobisisobutyronitrile (AIBN).
• the value is typically no more than approximately 30,000, and is preferably no more than 20,000, even more preferably 12,000 or lower, and is most preferably 10,000 or lower.
• the weight average molecular weight is preferably at least 4,000, and even more preferably 5,000 or greater.
• the weight average molecular weight (the polystyrene equivalent weight average molecular weight determined by gel permeation chromatography, this also applies below) of the component is typically 12,000 or lower, and is preferably 10,000 or lower.
• the weight average molecular weight is preferably at least 4,000, and even more preferably 5,000 or greater.
• the measured value of the contact angle at the surface of the resist film, following application of a developing solution to the surface of the resist film is preferably no higher than 40 degrees.
• the contact angle is also preferably at least 25 degrees, and even more preferably 30 degrees or greater. By ensuring that the contact angle is no higher than 40 degrees, the level of defects can be reduced.
• the measured value for the contact angle is preferably within a range from 30 to 40 degrees, even more preferably from 32 to 40 degrees, even more preferably from 35 to 40 degrees, and most preferably from 36 to 39 degrees.
• the contact angle can be altered by adjusting the nature and blend quantities of the structural units of the copolymer (A1′), or by adjusting the nature and blend quantities of the other components such as the component (B). Suitable methods include: increasing the blend quantities of structural units with hydrophilic regions, such as the structural unit (a2′) and the structural unit (a3′); selecting an acid generator that contains a hydrophilic group as the component (B); and adding a compound that contains a hydrophilic group as an additive. If the conditions of the first aspect are also satisfied, then adjustment of the contact angle is comparatively simple.
• the contact angle is measured in the manner described below.
• the level of defects can be reduced. Furthermore, the required lithography characteristics can also be obtained. Moreover, the sensitivity also improves. Furthermore, the required lithography characteristics can also be obtained using a shrink process described below.
• a resist pattern is obtained by applying the positive resist composition to a substrate, conducting a prebake, performing selective exposure, and then conducting PEB (post exposure baking) and performing alkali developing, but in the alkali developing step, following dissolution and removal of the exposed portions of the resist using the alkali developing solution, any residual developing solution and the like is usually removed by rinsing with pure water.
• PEB post exposure baking
• the positive resist composition of this third aspect generates a resist film that exhibits a small contact angle at the resist surface, meaning the surface is readily wet (has a high level of hydrophilicity)
• the affinity with comparatively hydrophobic solid components that can cause defects is reduced, meaning these deposits and residual substances can be readily removed from the resist film surface during the alkali developing and rinsing steps, thereby leading to a reduction in the level of defects.
• a method for forming a resist pattern according to the present invention can be conducted, for example, in the manner described below.
• a positive resist composition described above is first applied to a support such as a silicon wafer using a spinner or the like, a prebake is then conducted under temperature conditions of 80 to 150° C., for a period of 40 to 120 seconds, and preferably for 60 to 90 seconds, and following selective exposure (irradiation) of the thus obtained film with an ArF exposure apparatus or the like, by irradiating ArF excimer laser light through a desired mask pattern, PEB (post exposure baking) is conducted under temperature conditions of 80 to 150° C., for a period of 40 to 120 seconds, and preferably for 60 to 90 seconds. Subsequently, developing is conducted using an alkali developing solution such as a 0.1 to 10% by weight aqueous solution of tetramethylammonium hydroxide. In this manner, a resist pattern that is faithful to the mask pattern can be obtained.
• PEB post exposure baking
• An organic or inorganic anti-reflective film may also be provided between the support (substrate) and the applied layer of the resist composition.
• substrates for electronic componentry as well as substrates on which a predetermined wiring pattern has already been formed.
• suitable substrates include silicon wafers, metal-based substrates such as copper, chrome, iron, and aluminum, as well as glass substrates.
• Suitable materials for the wiring pattern include copper, solder, chrome, aluminum, nickel, and gold.
• a positive resist composition according to the present invention is particularly effective for use with an ArF excimer laser.
• a positive resist composition of the present invention can be used favorably within a shrink process detailed below. In other words, even when applied to a shrink process, the composition is able to yield favorable lithography characteristics.
• the applicants of the present invention have previously proposed a shrink process that includes the steps of forming a resist pattern on top of a support, forming a water-soluble coating on top of the resist pattern, and then shrinking this water-soluble coating by heat treatment and using the heat shrinkage effect to narrow the resist pattern size (for example, see Japanese Unexamined Patent Application, First Publication No. 2003-107752 and Japanese Unexamined Patent Application, First Publication No. 2003-202679).
• the shrink process is a method in which, following the covering of a resist pattern with a water-soluble coating, this water-soluble coating is shrunk by heat treatment, and this heat shrinkage action is used to narrow the spacing of the resist pattern.
• a method for forming a resist pattern that includes the conducting of a shrink process can be conducted, for example, in the manner described below.
• a resist pattern is formed using the general type of method described above.
• a water-soluble coating formation agent containing a water-soluble polymer or the like is applied to the surface of the resist pattern formed on the support, preferably forming a laminate in which the water-soluble coating covers the entire surface of the resist pattern.
• the support may be subjected to a prebake at a temperature of 80 to 100° C. for a period of 30 to 90 seconds.
• the application of the water-soluble coating formation agent can be conducted using a known method used in the formation of conventional resist layers and the like.
• an aqueous solution of the coating formation agent can be applied to the resist pattern using a spinner or the like.
• the thickness of the water-soluble coating is preferably either similar to the height of the photoresist pattern, or of a height sufficient to cover the pattern, and is typically within a range from approximately 0.1 to 0.5 ⁇ m.
• the thus obtained laminate is subjected to heat treatment, causing the water-soluble coating to undergo heat shrinkage.
• the side walls of the resist pattern that contact the water-soluble coating are pulled together, thereby narrowing the spacing (between patterns) of the resist-free portions within the resist pattern.
• the pattern can be reduced in size.
• the heat treatment is conducted at a temperature that is sufficient to cause shrinkage of the water-soluble coating, and is conducted at a heating temperature and for a heating period that does not cause fluidization of the resist.
• the heating temperature is preferably set to a value that is from 3 to 50° C. lower, and even more preferably approximately 5 to 30° C. lower, than the temperature (the fluidization temperature) at which heat treatment starts to causes spontaneous flow of the resist pattern formed on the support. Moreover, if the shrinking performance of the water-soluble coating is also taken into consideration, then a preferred heat treatment is typically conducted within a temperature range from 80 to 160° C., and preferably from 130 to 160° C. In the positive resist composition of the first aspect, the pattern is able to be narrowed even when the heating temperature is set to a comparatively low temperature.
• Favorable temperature conditions are typically within a range from 70 to 150° C.
• the fluidization temperature of a resist pattern varies depending on the nature and blend quantities of the components contained within the resist composition.
• the heating time varies depending on the heating temperature, but is typically within a range from 30 to 90 seconds.
• the water-soluble coating remaining on the resist pattern is removed by washing with an aqueous solvent, and preferably with pure water, for 10 to 60 seconds.
• the water-soluble coating is easily removed by washing with water, and is able to be completely removed from the support and the resist pattern.
• the water-soluble coating formation agent contains a water-soluble polymer.
• a water-soluble coating formation agent containing this type of water-soluble polymer is ideal for use within the shrink process.
• the water-soluble polymer used is preferably selected from amongst acrylic-based polymers, vinyl-based polymers, cellulose derivatives, alkylene glycol-based polymers, urea-based polymers, melamine-based polymers, epoxy-based polymers and amide-based polymers.
• Acrylic-based polymers refer to polymers that contain an acrylic-based monomer
• vinyl-based polymers refer to polymers that contain a vinyl-based monomer
• cellulose-based polymers refer to polymers that contain a cellulose-based monomer
• alkylene glycol-based polymers refer to polymers that contain an alkylene glycol-based monomer
• urea-based polymers refer to polymers that contain a urea-based monomer
• melamine-based polymers refer to polymers that contain a melamine-based monomer
• epoxy-based polymers refer to polymers that contain an epoxy-based monomer
• amide-based polymers refer to polymers that contain an amide-based monomer.
• These polymers can be used either alone, or in mixtures of two or more different polymers.
• acrylic-based polymers include polymers or copolymers containing structural units derived from monomers such as acrylic acid, acrylamide, methyl acrylate, methacrylic acid, methyl methacrylate, N,N-dimethylacrylamide, N,N-dimethylaminopropylmethacrylamide, N,N-dimethylaminopropylacrylamide, N-methylacrylamide, diacetone acrylamide, N,N-dimethylaminoethyl methacrylate, N,N-diethylaminoethyl methacrylate, N,N-dimethylaminoethyl acrylate, and acryloyl morpholine.
• monomers such as acrylic acid, acrylamide, methyl acrylate, methacrylic acid, methyl methacrylate, N,N-dimethylacrylamide, N,N-dimethylaminopropylmethacrylamide, N,N-dimethylaminopropylacrylamide, N-methylacryl
• suitable vinyl-based polymers include polymers or copolymers containing structural units derived from monomers such as morpholine, N-vinylpyrrolidone, vinylimidazolidinone, and vinyl acetate.
• Suitable cellulose derivatives include hydroxypropyl methylcellulose phthalate, hydroxypropyl methylcellulose acetate phthalate, hydroxypropyl methylcellulose hexahydrophthalate, hydroxypropyl methylcellulose acetate succinate, hydroxypropyl methylcellulose, hydroxypropyl cellulose, hydroxyethyl cellulose, cellulose acetate hexahydrophthalate, carboxymethylcellulose, ethylcellulose, and methylcellulose.
• alkylene glycol-based polymers include addition polymers or addition copolymers of monomers such as ethylene glycol or propylene glycol.
• Suitable urea-based polymers include polymers containing structural units derived from monomers such as methylolated urea, dimethylated urea, and ethylene urea.
• suitable melamine-based polymers include polymers containing structural units derived from monomers such as methoxymethylated melamine, methoxymethylated isobutoxymethylated melamine, and methoxyethylated melamine.
• water-soluble epoxy-based polymers and nylon-based polymers and the like can also be used.
• water-soluble polymers those containing at least one polymer selected from a group consisting of alkylene glycol-based polymers, cellulose-based polymers, vinyl-based polymers and acrylic-based polymers is preferred, and acrylic-based polymers are the most preferred as they also offer simple pH adjustment.
• acrylic-based polymers are the most preferred as they also offer simple pH adjustment.
• using a copolymer of an acrylic-based monomer and another non-acrylic monomer is preferred, as such copolymers enable efficient narrowing of the photoresist pattern size, while maintaining the shape of the photoresist pattern during the heat treatment.
• Water-soluble polymers that include N-vinylpyrrolidone as a proton donor monomer and acrylic acid as a proton acceptor monomer are particularly preferred as they exhibit a particularly large shrinkage ratio on heating.
• the water-soluble polymer preferably contains structural units derived from acrylic acid and structural units derived from vinylpyrrolidone.
• the blend proportion of the acrylic-based polymer is preferably greater than that of the other structural polymers.
• an acidic compound such as p-toluenesulfonic acid or dodecylbenzenesulfonic acid can also be added.
• the water-soluble coating formation agent preferably also contains a surfactant.
• a surfactant By using a surfactant, the occurrence of defects can be effectively prevented.
• the water-soluble coating formation agent may also contain an optional water-soluble amine.
• an additional non-amine-based water-soluble organic solvent may also be added to the water-soluble coating formation agent if desired.
• the water-soluble coating formation agent is preferably used in the form of a solution within either water or a water-alcohol-based solvent (in which the alcohol concentration is no higher than approximately 30% by weight relative to the water), with a concentration of 3 to 50% by weight, and even more preferably from 5 to 20% by weight.
• copolymer, component (B), component (D), and organic solvent listed below were mixed together to form a solution, thus yielding a positive resist composition with a solid fraction concentration of 8% by weight.
• the contact angle for a resist film formed from this resist composition, following application of a developing solution, was 37.7 degrees (37.7°). Furthermore, the Tg value for the copolymer was 120° C.
• the Tg value (glass transition temperature) was measured using a thermal analysis apparatus TG/DTA6200 (manufactured by Seiko Instruments, Inc.) under conditions including a rate of temperature increase of 10° C./minute.
• Copolymer 100 Parts by Weight
• a copolymer formed from the structural units represented by a chemical formula (1) shown below, in which the molar ratio l/m/n 40 mol %/40 mol %/20 mol %, with a weight average molecular weight of 10,000, and a polydispersity [Mw (weight average molecular weight)/Mn (number average molecular weight)] of 2.0.
• Component (B) 3.5 Parts by Weight
• Component (D) 0.1 Parts by Weight
• the copolymer, component (B), component (D), and organic solvent listed below were mixed together to form a solution, thus yielding a positive resist composition with a solid fraction concentration of 8% by weight.
• the contact angle for a resist film formed from this resist composition, following application of a developing solution, was 51.8 degrees (51.8°).
• the Tg value for the copolymer was 138° C.
• Copolymer 100 Parts by Weight
• a copolymer formed from the structural units represented by a chemical formula (2) shown below, in which the molar ratio l′/m′/n′ 40 mol %/40 mol %/20 mol %, with a weight average molecular weight of 10,000, and a polydispersity [Mw (weight average molecular weight)/Mn (number average molecular weight)] of 2.0.
• the resist compositions of the example 1 and the comparative example 1 were evaluated in the manner described below.
• An organic anti-reflective film composition “ARC-29A” (a product name, manufactured by Brewer Science Ltd.) was applied to the surface of an 8-inch silicon wafer using a spinner, and the composition was then baked and dried on a hotplate at 205° C. for 60 seconds, thereby forming an organic anti-reflective film with a film thickness of 77 nm.
• the positive resist composition was then applied to the surface of this anti-reflective film using a spinner, and was then prebaked (PAB) and dried on a hotplate at 110° C. for 90 seconds, thereby forming a resist layer with a film thickness of 225 nm.
• the resist was then subjected to PEB treatment at 100° C. for 90 seconds, subsequently subjected to puddle development for 60 seconds at 23° C. in a 2.38% by weight aqueous solution of tetramethylammonium hydroxide, and was then washed for 20 seconds with water, and dried, thus forming a resist pattern.
• the sensitivity at the time of formation of each of these patterns was (1-1) 23.0 mJ/cm 2 , (1-2) 30.5 mJ/cm 2 , (2-1) 32.0 mJ/cm 2 , and (2-2) 42.5 mJ/cm 2 , indicating a higher level of sensitivity for the resist composition of the example.
• the positive resist compositions of the example 1 and the comparative example 1 were each applied directly to the surface of an 8-inch silicon wafer using a spinner, and were then prebaked (PAB) and dried on a hotplate at 105° C. for 90 seconds, thereby forming a resist layer with a film thickness of 220 nm in each case.
• PAB prebaked
• Each resist was then subjected to PEB treatment at 100° C. for 90 seconds, subsequently subjected to puddle development for 60 seconds at 23° C. in a 2.38% by weight aqueous solution of tetramethylammonium hydroxide, and a rinse liquid was then dripped onto the resist for 1 second at 1,000 rpm and then for 15 seconds at 500 rpm (enforced conditions for increasing the likelihood of defect occurrence), before the resist was dried to form a resist pattern.
• a normal rinse process was conducted, in which the rinse liquid was dripped onto the resist for 10 seconds at 2,000 rpm and then for 50 seconds at 1,000 rpm.
• the pattern was formed as a dense hole pattern with a hole diameter of 300 nm (a pattern in which holes of diameter 300 nm were spaced at 300 nm intervals).
• the resist was measured using a surface defect inspection device KLA2351 (a product name) manufactured by KLA Tencor Corporation, and evaluation of the number of defects within the wafer revealed a value of 257 defects per 8-inch wafer for the example 1, and 22,535 defects per 8-inch wafer for the comparative example 1.
• KLA2351 a product name manufactured by KLA Tencor Corporation
• Resist patterns were formed in the same manner as described above in the section entitled “Evaluation of Resolution”, and the depth of focus (DOF) was then measured.
• the heating temperature for the shrink process was set to 140° C. for the example 1 and 150° C. for the comparative example 1.
• the pattern was able to be narrowed even when the shrink process temperature was lowered. It is thought that this observation is due to that fact that the Tg value of the resin of the example 1 is lower than the Tg value of the resin of the comparative example 1.
• Water-soluble coating formation agent FSC5000EX (a product name, manufactured by Tokyo Ohka Kogyo Co., Ltd.)
• the depth of focus characteristics in the case of the resist patterns (1-1) and (2-1) were superior to those of the comparative example 1.
• the pattern shapes in the example 1 were no different from those of the comparative example 1, indicating that conventional levels of characteristics were able to be maintained.
• the sensitivity was higher in the example 1 than in the comparative example 1, an improvement in throughput can be anticipated.
• the example 1 exhibited no differences from the comparative example 1, confirming that conventional levels of characteristics were able to be maintained.
• resist composition 1 (1) With the exception of using a copolymer 2-1 described below as the component (A), a resist composition was produced in the same manner as the example 1. This composition was termed the resist composition 1.
• the measured value of the contact angle for this resist composition 1 was 44.45 degrees (44.45°) (comparative example 2).
• Copolymer 2-1 100 Parts by Weight
• a copolymer formed from the structural units represented by the chemical formula (1) shown above, in which the molar ratio l/m/n 40 mol %/40 mol %/20 mol %, with a weight average molecular weight of 10,000, and a polydispersity [Mw (weight average molecular weight)/Mn (number average molecular weight)] of 2.0.
• Copolymer 2-2 100 Parts by Weight
• a copolymer 2-2 formed from the same structural units, in the same proportions, as the copolymer 2-1, with the same weight average molecular weight and the same polydispersity, and differing from the copolymer 2-1 only in terms of the production lot.
• the measured value of the contact angle for this resist composition 2 was 33.72 degrees (33.72°) (example 2).
• the measured value of the contact angle for this resist composition 3 was 38.87 degrees (38.87°) (example 3).
• the result for the resist composition 1 was 27,598 defects per 8-inch wafer.
• the result for the resist composition 2 was 69 defects per 8-inch wafer.
• the result for the resist composition 3 was 354 defects per 8-inch wafer.
• the defect evaluation results for the resist compositions 2 and 3 (the examples 2 and 3), in which the measured value of the contact angle was no higher than 40 degrees, were particularly favorable.
• the defect evaluation result for the resist composition 1 (the comparative example 2) in which the measured value of the contact angle exceeded 40 degrees was poor. From these results it is evident that even if copolymers formed from the same structural units in the same proportions are used, the measured value of the contact angle can vary considerably depending on factors such as the production lot.
• resists for which the contact angle is large exhibit particularly poor defect characteristics.
• resist compositions of comparative examples 3 through 6 were prepared in the manner described below, and subsequently evaluated for defects.
• the defect evaluation result is favorable for those resist compositions for which the measured value of the contact angle is no higher than 40, but is poor for those compositions in which the measured value exceeds 40.

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